105,579 research outputs found
Rank p ? 1 mod-p H-spaces
No full textDifferent constructions by Cooke, Harper and Zabrodsky and by Cohen and Neisendorfer produce torsion free finite p-local H-spaces of rank l < p ? 1. The first construction goes through when l = p ? 1 and we show the second does as well. However, the space produced need not be an H-space. We give a criterion for when an H-space is obtained. In the special case of rank 2 mod-3 H-spaces, we also give a practical test for when the criterion holds, and use this to give many new examples of finite H-spaces
A nonlinear parabolic-hyperbolic system for contact inhibition of cell-growth
No full textWe consider a tumor growth model involving a nonlinear system of partial differential equations which describes the growth of two types of cell population densities with contact inhibition. In one space dimension, it is known that global solutions exist and that they satisfy the so-called segregation property: if the two populations are initially segregated - in mathematical terms this translates into disjoint supports of their densities - this property remains true at all later times. We apply recent results on transport equations and regular Lagrangian flows to obtain similar results in the case of arbitrary space dimension
Standing and travelling waves in a parabolic-hyperbolic system
No full textWe consider a nonlinear system of partial differential equations which describes the dynamics of two types of cell densities with contact inhibition. After a change of variables the system turns out to be parabolic-hyperbolic and admits travelling wave solutions which solve a 3D dynamical system. Compared to the scalar Fisher-KPP equation, the structure of the travelling wave solutions is surprisingly rich and to unravel part of it is the aim of the present paper. In particular, we consider a parameter regime where the minimal wave velocity of the travelling wave solutions is negative. We show that there exists a branch of travelling wave solutions for any nonnegative wave velocity, which is not connected to the travelling wave solution with minimal wave velocity. The travelling wave solutions with nonnegative wave velocity are strictly positive, while the solution with minimal one is segregated in the sense that the product uv vanishes
Damage threshold investigation using grazing incidence irradiation by hard X-ray free electron laser
No full textT. Koyama, H. Yumoto, K. Tono, T. Sato, T. Togashi, Y. Inubushi, T. Katayama, J. Kim, S. Matsuyama, H. Mimura, M. Yabashi, K. Yamauchi, and H. Ohashi "Damage threshold investigation using grazing incidence irradiation by hard x-ray free electron laser", Proc. SPIE 8848, Advances in X-Ray/EUV Optics and Components VIII, 88480T (27 September 2013); https://doi.org/10.1117/12.2025377
A nonlinear parabolic-hyperbolic system for contact inhibition and a degenerate parabolic Fisher KPP equation
No full textWe consider a mathematical model describing population dynamics of normal and abnormal cell densities with contact inhibition of cell growth from a theoretical point of view. In the first part of this paper, we discuss the global existence of a solution satisfying the segregation property in one space dimension for general initial data. Here, the term segregation property means that the different types of cells keep spatially segregated when the initial densities are segregated. The second part is devoted to singular limit problems for solutions of the PDE system and traveling wave solutions, respectively. Actually, the contact inhibition model considered in this paper possesses quite similar properties to those of the Fisher-KPP equation. In particular, the limit problems reveal a relation between the contact inhibition model and the Fisher-KPP equation
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Regulation of chloroplast development in relation to leaf age and N-, P- and S-nutrition
No full textDietz K-J, Schönrock M, Heilos L, Mimura T. Regulation of chloroplast development in relation to leaf age and N-, P- and S-nutrition. In: Tazawa M, Katsumi M, Masuda Y, Okamoto H, eds. Plant Water Relations and Growth Under Stress. Tokyo: Myu K.K.; 1989: 129-132
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Strain distribution analysis of sputter-formed strained Si by tip-enhanced Raman spectroscopy
No full textSimultaneous nanometer-scale measurements of the strain and surface undulation distributions of strained Si (s-Si) layers on strain-relief quadruple-Si1-xGex-layer buffers, using a combined atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy (TERS) system, clarify that an s-Si sample formed by our previously proposed sputter epitaxy method has a smoother and more uniformly strained surface than an s-Si sample formed by gas-source molecular beam epitaxy. The TERS analyses suggest that the compositional fluctuation of the underlying Si1-xGex buffer layer is largely related to the weak s-Si strain fluctuation of the sputtered sampl
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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